Improvement in steam-boiler furnaces



UNITED STATES PATENT OEEIoE.

MICHAEL A. FOSTER, OF ST. LOUIS, MISSOURI.

IMPROVEMENT IN STEAM-BOILER FURNACES.

Specification forming part of Letters Patent No. 138,875, dated May 13, 1873; application filed March 20, 1873.

To all whom it may concern:

Be it known that I, MICHAEL A. FosTER, of the city and county of St. Louis and State of Missouri, have invented a certain Improvement in Steam-Boiler Furnaces, of which the following is a specification:

My invention consists in the arrangement of a series of pipes or passages longitudinally in the fire bed of steam boiler furnaces. The forward ends are curved downward and project into a semi-elliptical smokepit. At the rear end the pipes open into a second semi-elliptical smoke-pit for the collection of the smoke or unconsumed gases,

and from which the said gases are forcedback through the pipes or passages (by a series of steam-jets) into the forward smokepit, where the steam and gases are mixed with a supply of heated air forced by steamjets into the said smoke-pit through pipes arranged longitudinally in the fire-bed and taking air-supply through the side wall of the furnace. The pipes or passages for conducting smoke and gases, and also the airpipes, are provided withflap-valves or dampers secured on a common shaft arranged transversely underneath the fire-bed, and extending through the side wall, where it carries a lever, by which it is operated.

The steam-pipe which supplies steam to the jets is provided with a valve to shut off steam when desired.

Figure 1 is a perspective view of a steamboiler furnace with part of a side wall removed to show my improvements. Fig. 2 is a longitudinal section.

A is the forward smoke-pit of the furnace, of semi elliptical form, preferably. B are a series of square or round pipes (square preferred) or passages arranged longitudinally in the fire-bed of the furnace. The forward ends of said pipes are curved downward and project into the forward smoke-pit A, so as to discharge into the same. 0 is a steam coil or pipe arranged transversely in the rear smoke-pit D and having small jet-pipes c, which discharge steam into the rear ends of the pipes B and cause a forward current therein. The pipe 0 is provided with a valve to shut off steam from the jets c. The pit D, like that, A, should be semi-elliptical in section, and in it collect the heavier gases passing over the fire-bed, and are forced by the steam-jets into the rear ends of the pipes B, (which open into said pit,) and are carried forward along said pipes and projected downwardly and forwardly into the pit A. The fire-bed slopes downward from the rear side of the pit to the front side of the rear pit D, as shown. E are square or round airpipes arranged longitudinally in the fire-bed, the rear ends of which pass through the side walls of the furnace, the other ends being curved and projecting transversely into the smoke-pit A, so as to discharge the heated air into the said pit. e are steam jets for forcing air through the pipes E. The smokepassages or pipes B, and air-pipe E are provided with dampers b (see Fig. 2,) arranged 011 a common transverse shaft b underneath the fire-bed. The shaft has outside the furnacewall a suitable operative handle or lever.

The operation of my improvement is as follows: The 'unconsumed inflammable gases passing off from the fire pass back through, the space between the fire-bed and the boiler v and the heavier portions (containing the most inflammable gases) are collected in the pit D to be forced by the steam-jets 0 through the pipes B into the forward smoke pit A where said gases are mixed with fresh heated air, introduced through the pipes E by jets e. The mixed air and inflammable gases passing up from the smoke-pit A come in contact with the flame from the fire-box, and the gases are ignited.

Claims.

1. The return-pipes or passages B, in combination with steam-jets 0 and smoke-pit A, substantially as set forth.

2. The combination of the pipes B, jets c, and semi-elliptical smoke-pit A, substantially as set forth.

3. The combination of the pipes B, steam- 

